Free Radicals Resulting from Plasma Polymerization and Plasma Treatment

A glass tube is subjected to plasma treatment (non-polymerizable plasma) or plasma coating (polymerizable plasma). Unpaired spins generated in the glass substrate alone, and in both substrate and coating for the second case, are detected by ESR It is shown that for both polymerizable and nonpolymerizable plasmas the substrate's unpaired spins (glass radicals) are caused, in large part, by UV radiation from the plasma. In the case of plasma coating, the glass radicals are formed at the outset of the polymerization because the coating increasingly absorbs the UV radiation as deposition continues. High concentrations of free radicals in the coating appear to be correlated with a high tendency to polymerize, while high values of substrate radical surface concentration are related to high levels of UV intensity in the plasma.